JP2006025676A - Rubber crawler-type mower - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mower enabling grass/trees to be cut without trouble along a contour line through maximally suppressing the tendency of the machine body's sliding down toward the lower side in a weak and inclined ground in particular. <P>SOLUTION: The mower comprises the machine body A equipped with a pair of left and right rubber crawlers and a mowing unit U mounted on the front portion of the machine body A, wherein the mowing unit U is of rotary type with cutting blades 41 rotating around a vertical rotating shaft 46. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rubber crawler type mower having a rotary mowing unit mounted on the front portion of an airframe equipped with a rubber crawler.

  As a conventional rubber crawler type mower having a mower unit mounted on the front part of a machine body equipped with a rubber crawler, for example, as shown in Patent Document 1, a plurality of hammer knives are attached to a horizontal rotating shaft as the mower unit. There is a thing of the structure. The rubber crawler mower has the advantage of excellent running stability and straight running because the machine is run by a pair of left and right rubber crawlers. In addition, the hammer knife type mowing unit has a configuration in which a hammer knife that rotates at high speed is impacted against the vegetation to be cut, and the vegetation is cut. Trees can also be cut (broken) at the same time, and there is an advantage that the ability of mowing work is high, so that the trees can be surely cut.

  However, the above-mentioned hammer knife type rubber crawler mower is effective on solid normal ground, but the weight of the hammer knife type mowing unit is heavy on soft ground, especially on soft slope ground. The main reason was that it was difficult to cut contour lines. That is, since the hammer knife type mowing unit has a large overall weight, the center of gravity position of the entire mowing machine including the airframe and the mowing unit is shifted to the front of the airframe (the mowing unit side), and the mowing unit Since the hammer knife rotates around the horizontal rotation axis, the position of the center of gravity of the mowing unit also increases, and the position of the center of gravity of the entire mowing machine increases. For this reason, when contour cutting is performed on soft sloped ground, the mowing unit attached to the front end of the fuselage tends to slip to the lower side, and the driver periodically performs track correction so that the driver runs along the contour line. Therefore, there is a problem that it is difficult to cut the contour line and the driving operation is difficult.

On the other hand, there is a mower with a rotary-type mowing unit in which the cutter rotates about a vertical axis, mounted on the tip of the airframe, but this type of mower has a configuration that travels with a pair of wheels. . For this reason, when cutting a contour line of vegetation on soft slope ground with a wheel-type mower, the mowing unit frequently slips to the lower side of the slope, so that the driver travels along the contour line. In addition, it was necessary to perform mowing work while frequently correcting the trajectory, and it was difficult to cut the contour lines and it was difficult to operate.
Japanese Patent Publication No.8-18572

  An object of the present invention is to provide a mower that can cut a plant and trees along a contour line without any hindrance, while suppressing the tendency of the machine body to slip to a lower side as much as possible, particularly on soft sloped ground.

  The invention of claim 1 for solving the above-mentioned problem is a mowing machine comprising a machine body having a pair of left and right rubber crawlers and a mowing unit mounted on the front of the machine body, wherein the mowing unit has a vertical axis. It is characterized by being a rotary type in which the cutting blade rotates around the center.

  According to the invention of claim 1, the combination of the rubber crawler structure machine and the rotary type mowing unit is compared with the mower according to the combination of the machine equipped with the rubber crawler and the hammer knife type mowing unit. The center of gravity along the front-rear direction of the entire mower can be shifted to the front side of the aircraft (the side where the driver is located), and the center of gravity along the vertical direction can be lowered. In addition, the entire mower can be significantly reduced in weight compared to a hammer knife type mower. For this reason, in combination with the movement (displacement) of the center of gravity of the entire mower described above and the weight reduction of the mower, the entire mower is low when performing mowing work on an inclined ground, particularly a soft inclined ground. The tendency of slipping down to the side is suppressed (reduced), and the straight traveling performance and traveling stability of the rubber crawler structure body are increased, so that contour cutting of plants can be stably performed on soft sloped ground. . Therefore, the driving operation of the driver who performs the driving work behind the aircraft is also facilitated. Also, even with a mower equipped with a rotary type mowing unit, in a mower equipped with a wheel structure, the mower should slide down to the lower side of the ground, and the driver should follow the contour line. Compared to the need for frequent trajectory correction, the straight running performance and running stability on soft sloped ground are greatly improved, and the tendency of the aircraft to slip to the lower side is greatly suppressed, It becomes easy to carry out contour cutting.

  According to a second aspect of the present invention, in the first aspect of the invention, the mowing unit includes two cutting blades arranged at a predetermined interval in the left-right direction, and a rear side of the two cutting blades. In addition, a total of three cutting blades including one cutting blade disposed at an intermediate position between the two cutting blades along the left-right direction is provided.

  According to the invention of claim 2, by arranging the three cutting blades constituting the mowing unit as described above, it is in front of the two cutting blades arranged at predetermined intervals in the left-right direction. In addition, compared with the case where one cutting blade is disposed at the middle position in the left-right direction of the two cutting blades, the total length of the mowing machine having a rotary mowing unit attached to the front of the machine body can be shortened. Thus, the position of the center of gravity in the front-rear direction of the entire mower is further attached to the front side of the fuselage (the side where the driver is located). As a result, the traveling performance along the contour line direction on the slope is further improved, and the driving operation of the airframe is facilitated.

  According to a third aspect of the present invention, in the invention according to the first or second aspect, the mowing unit is normally supported horizontally by a gravitational action with respect to the frame of the fuselage, and the tip portion is an obstacle or the like. When hitting, it is characterized in that it is supported so as to be able to rotate only upward from the horizontal state in order to avoid the obstacle.

  According to the invention of claim 3, since the mowing unit is configured to rotate only upward from the horizontal position as the work position, an obstacle such as a large mountain portion existing along the contour direction during mowing work. If the mowing unit hits the inclined surface due to the difference in the inclination angle between the aircraft and the mowing unit when climbing or descending the inclined surface, avoid obstacles etc. Since the mowing unit pivots upward with respect to the airframe, the mowing operation can be performed without any hindrance, and the inclined surface can be climbed or descended.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the tip portion of the mowing unit is not grounded even in a mowing state where the cutting height is the lowest, and the grounding portion of the aircraft is not grounded. A grounding ring that can be grounded only on an inclined surface is provided.

  According to the invention of claim 4, the grounding wheel at the tip of the mowing unit is not grounded even in a normal mowing state where the cutting height is the lowest, so when performing contour cutting on an inclined land such as a dike slope, When turning at the cutting end, the grounding wheel does not hit the ground and scratch. On the other hand, when there is a mountain part along the contour direction, when climbing or descending the slope, if there is a surface inclined with respect to the grounding part of the fuselage, the grounding wheel at the tip of the mowing unit is the mountain part. Alternatively, the grass cutting unit is rotated upward with respect to the airframe by hitting the inclined surface, so that the grass mower can run. In addition, since the total load of the mowing unit acts as a cantilever on the front of the aircraft, and the actual weight of the aircraft increases, the straight traveling performance of the aircraft including the rubber crawler is improved.

  The invention of claim 5 is characterized in that, in any of the inventions of claims 1 to 4, the mowing unit is connected to the airframe via a parallel link mechanism.

  According to invention of Claim 5, a mowing unit can be raised / lowered with respect to a body with a simple mechanism, maintaining a horizontal state.

  Further, the invention of claim 6 is the invention of claim 5, in order to transmit the power of the engine mounted on the airframe to the mowing unit, the input shaft of the gear box mounted on the cover body of the mowing unit; The rotation fulcrum of the mowing unit that is rotatably supported by the tip vertical link that constitutes the parallel link mechanism is arranged on the same axis.

  According to the invention of claim 6, the input shaft of the gear box mounted on the cover body of the mowing unit, and the rotation fulcrum of the mowing unit supported by the movable vertical link at the tip of the parallel link mechanism Because the mowing unit rotates relative to the aircraft, the endless belt hung between the output shaft pulley of the engine and the input shaft pulley of the gearbox is Not loose at all. As a result, the power of the engine is always transmitted to the mowing unit without any problem regardless of the inclination angle of the mowing unit with respect to the airframe.

  The present invention provides a mowing machine comprising a machine body having a pair of left and right rubber crawlers and a mowing unit mounted on the front portion of the machine body, wherein the mowing unit is a rotary type in which a cutting blade rotates about a vertical axis. Therefore, compared to the hammer knife type mowing unit, the center of gravity of the entire mowing machine can be shifted to the front side along the longitudinal direction of the fuselage, and it can also be lowered. In the case of cutting along the contour line, the traveling stability and straightness of the aircraft are enhanced, and the tendency of the aircraft to slip to the lower side is greatly suppressed. For this reason, the above-mentioned vegetation of the soft slope ground can be efficiently cut along the contour lines, and the driving operation performed by the driver following the fuselage is facilitated.

  Hereinafter, the present invention will be described in more detail with reference to the best mode for carrying out the present invention. FIG. 1 is a schematic perspective view of an entire rubber crawler mower according to the present invention, FIGS. 2 and 3 are a side view and a plan view of the rubber crawler mower, respectively, and FIG. FIG. 5 is a plan view showing a power transmission system. 1 to 4, a rubber crawler mower according to the present invention maintains a horizontal state with a body A having a pair of rubber crawlers 1 on both right and left sides, and a parallel link mechanism K at the front of the body A. The rotary mowing unit U is mounted so as to be movable up and down. The rotary-type mowing unit U includes a plurality of (three in the embodiment) cutting blades 41, and each cutting blade 41 is attached to the lower end portion of the vertical rotation shaft 46 and is an axis of the vertical rotation shaft 46. It is the structure which rotates in the surface perpendicular | vertical with respect to and cuts vegetation.

  Further, an engine E is mounted at the center in both the front-rear direction and the width direction of the airframe A, and the output of the engine E is transmitted to each rubber crawler 1 and the mowing unit U by a transmission mechanism, respectively. The rubber crawler 1 circulates in a predetermined direction to move the machine body A forward or backward, and rotate each cutting blade 41 of the mowing unit U in a predetermined direction (clockwise as viewed from above). A rear frame 2 is provided at the rear of the machine body A, and a handle 3 is attached to the rear upper end of the rear frame 2. A transmission 4 is arranged behind the engine E in the airframe A, and between a one 6a of a double pulley 6 attached to the drive shaft 5 of the engine E and a pulley 8 attached to the input shaft 7 of the transmission 4. An endless belt 9 is engaged with the power, and the power of the engine E is transmitted to the input shaft 7 of the transmission 4 and is greatly decelerated in the transmission 4 and output from the output shaft 11. Below the input shaft 7 of the transmission 4, an output shaft 11 longer than the entire width of the machine body A is disposed, and the endless rubber crawler 1 travels around by the sprockets 12 attached to both ends of the output shaft 11. Is done.

  Further, a mowing unit U is mounted on the front portion of the airframe A through a parallel link mechanism K so as to be movable up and down. The change link mechanism K is composed of a pair of parallel link mechanisms K ′ having the same structure and disposed at both ends in the width direction of the front portion of the airframe A. The parallel link mechanism unit K ′ includes a fixed vertical link 13 fixed vertically to both ends in the width direction of the front portion of the airframe A, and a movable vertical link 14 disposed in front of the fixed vertical link 13 at a predetermined interval. And a pair of upper and lower equal-length connecting links 15 that connect the fixed vertical link 13 and the movable vertical link 14. A pair of connecting arms 43 are integrally attached to the rear side of the cover main body 42 of the mowing unit U along the width direction of the machine body A, vertically upward. A bracket 44 is provided on the back side of the upper end of each connecting arm 43. It is fixed. The mowing unit U is rotatably connected to a pair of movable vertical links 14 constituting the parallel link mechanism K via a fulcrum pin 45 attached horizontally to the outside of the bracket 44. On the other hand, a cushion material bracket 16 is attached to the inside of the lower ends of the pair of movable vertical links 14, and the rear side of the lower end of the connecting arm 43 of the mowing unit U is applied to the front surface of the bracket 16. A cushioning material 17 is attached for keeping the entire mowing unit U in contact with it.

Further, a mowing unit U is mounted on the airframe A so as to be able to move up and down via a parallel link mechanism K. The airframe A has an elevating mechanism B for moving the mowing unit U up and down relative to the airframe A. It is installed. The elevating mechanism B includes rotating brackets 21 and 21 ′ integrally attached to a pair of upper connecting links 15 constituting a pair of parallel link mechanisms K ′ and free ends of the rotating brackets 21 and 21 ′. A connecting rod 22 connected to each other, a cutting height adjusting rod 24 for rotating the rotating bracket 21 around the fulcrum pin 23 to determine the height of the mowing unit U (the cutting height of the vegetation), and the rear part A rod 25 with a tension spring for connecting the frame 2 and one end of the connecting rod 22 to increase the rigidity of the one end of the connecting rod 22 is provided. A female screw body 32 is rotatably mounted on the outer surface of the rotating bracket 21 via a bracket 31, and a proximal end portion of a cutting height adjusting rod 24 having a distal end portion screwed to the female screw body 32 is formed at the base end portion. The bracket 33 attached to the rear frame 2 is pivotable and supported so as not to advance and retreat. Therefore, as shown in FIG. 6, when the cutting height adjusting rod 24 is rotated in a predetermined direction by the handle 34 attached to the base end portion of the cutting height adjusting rod 24, the upper portion constituting the parallel link mechanism K is The connecting link 15 is rotated about the fulcrum pin 23 in a predetermined direction, and the mowing unit U is moved up and down while maintaining the level to determine the cutting height H ₁ (H ₂ ) of the vegetation.

Next, the mowing unit U will be described in detail with reference to FIGS. The cover main body 42 has a shape in which each corner portion at the front two places of the horizontal rectangular shape is small and each corner portion at the two rear positions is chamfered, and three vertical rotation shafts 46 are supported by the main body top plate 47. A cutting blade 41 is attached to a lower end portion of each vertical rotation shaft 46 disposed below the main body top plate 47, and a portion projecting above the main body top plate 47 on each vertical rotation shaft 46. Each has a pulley 48 attached thereto. Two of the three cutting blades 41 are arranged at predetermined intervals along the width direction (left-right direction) of the machine body A, and the remaining one is behind the two cutting blades 41. And it is arrange | positioned along the width direction of the body A at the intermediate position of the two cutting blades 41 ahead. The arrangement of the three cutting blades 41 in this way shortens the overall length (L ₀ ) of the mower (see FIG. 11 (A)) compared to the arrangement shown in FIG. 11 (B). Thus, the position of the center of gravity of the entire mower is moved as close as possible to the rear part (the side where the driver is located) of the airframe A to improve the running stability and the straight running performance of the mower. It should be noted that the rotation trajectories of the two cutting blades 41 adjacent to each other among the three cutting blades 41 are overlapped by a predetermined amount along the width direction (lateral direction) of the machine body A, so that there is no uncut portion. It is.

  Further, as shown in FIGS. 2 to 5, the cover body 42 is located above the rear end of the cover body 42, and is moved up and down and rotated integrally with the cover body 42 at the center in the width direction of the machine body A. The endless belt 54 is hung between another pulley 6b attached to the drive shaft 5 of the engine E and the pulley 53 attached to the input shaft 52 of the gear box 49. It is disguised. The output shaft 55 of the gear box 49 protrudes vertically below the gear box 49 and is attached to a pulley 56 attached to the output shaft 55 and a vertical rotating shaft 46 to which the rear cutting blade 41 is attached. An endless belt 58 is hung between another pulley 57. Further, an endless belt 61 is hooked on each pulley 48 attached to a portion of each vertical rotation shaft 46 protruding upward from the main body top plate 47. By the transmission mechanism described above, the power of the engine E is converted to 90 ° in the transmission direction by the gear box 49, and then distributed to the vertical rotation shafts 46 by the belt transmission mechanism, and arranged below the cover body 42. The cutting blade 41 rotates at the same rotational speed in the same direction (clockwise as viewed from above in the embodiment). 3 and 4, 62 is a tension pulley that applies tension to the endless belt 61 at two locations, and 63 is a tension pulley that applies tension to the endless belt 58. In FIG. 2, reference numerals 75 and 76 denote tension pulleys that apply tension to the endless belts 9 and 54, respectively.

As shown in FIGS. 2 and 4, the shaft center C ₁ of the fulcrum pin 45 connecting the mowing unit U to the movable vertical link 14 and the mowing unit U are moved up and down and rotated integrally. The axis C ₂ of the input shaft 52 of the gear box 49 is arranged on the same axis. With this structure, when the mowing unit U rides on the protrusion 81 during the cutting operation (FIG. 8 (a)) or climbs or descends the slope slope 82, the mowing unit U is a part of the body A. Even if the grass cutting unit U rotates about the fulcrum pin 45 with respect to the airframe A when it hits a part with an inclination angle different from that of FIG. 8 (B), it is attached to the drive shaft 5 of the engine E. The endless belt 54 hung between the pulley 6a and the pulley 53 attached to the input shaft 52 of the gear box 49 does not loosen. For this reason, even when the mowing unit U rides on the protrusion 81 during the mowing operation, the transmission power of the engine E to the vertical rotation shafts 46 of the mowing unit U does not decrease at all (with respect to the airframe A). The mowing unit U is transmitted in the same state as the parallel state), and the cutting operation can be performed.

As shown in FIGS. 2 and 4, grounding rings 65 are attached to both ends in the width direction of the cover main body 42 of the mowing unit U via grounding ring arms 64. As shown in FIG. 5, the grounding ring 65 is provided at a height that does not contact even in the case of the shortest cutting height (H ₁ ), as shown in FIGS. When the tip of the mowing unit U hits when there is a mountain in front of the running line of the mower, or when climbing or descending on an inclined slope such as a river bank, The ring 65 is the part that hits first. The reason for this design is that when the cutting operation is performed while turning at both cutting edges in a place where vegetation is growing, including slope slopes such as river dikes, the mowing unit U during the turning This is to prevent the grounding ring 65 at the tip of the ground from scratching the ground (at the shortest cutting height (H ₁ ), the grounding ring 65 is not grounded, so the grounding wheel 65 does not scratch the ground when the mower turns) .

  Further, the mowing unit U that is rotatably connected to the movable vertical link 14 via a pair of fulcrum pins 45 is rotated largely upward as shown in FIG. It is necessary to maintain this posture. Therefore, a bracket 66 with a hole is provided integrally on the upper surface of the bracket 44 to which the fulcrum pin 45 is attached, and a bracket 67 with a hole is provided integrally on the inner surface of the movable vertical link 14 so as to rearward the mowing unit U. When the brackets 66, 67 with both holes are in a state of being pivoted largely upwards and connected with the connecting pins 68, the mowing unit U is maintained in the position of being largely lifted upward. It is possible. Further, stones hit by the high speed rotation of the cutting blade 41 are scattered on the front surface and both side surfaces of the mowing unit U from the cover main body 42 of the mowing unit U to prevent the danger of hitting nearby workers. A rubber cover 69 is hung down. A pulley 48 and the like disposed above the main body top plate 47 of the mowing unit U are covered with a cover 71. 2 and 4, 72 is a reinforcing rod for connecting the upper end of the connecting arm 43 and the main body top plate 47 to increase rigidity, and 73 is a mowing unit U for maintenance or the like. The handle | steering-wheel for lifting by hand when it rotates large upwards is shown. 2 and 3, 87 is a cutting blade lever for driving and cutting off the cutting blade 41 of the mowing unit U, and 88 is a brake force applied to the output shaft 11 of the transmission 4 during parking or the like. A brake lever to be added, and 89 is an accelerator lever. In FIGS. 1 and 4, reference numeral 90 denotes a reinforcing member for connecting the upper connecting links 15 constituting the pair of parallel link mechanisms K ′ to enhance the unity of each parallel link mechanism K ′. The connecting rod is shown.

The center of gravity (G ₀ ) of the mowing machine of the above embodiment in which the rotary type mowing unit U is mounted on the front part of the airframe A having a pair of left and right rubber crawlers 1 is the case where the mowing unit U is a hammer knife type. As compared with the above, the position of the center of gravity along the up-down direction is lowered while being shifted to the near side (side where the driver is located) along the front-rear direction of the airframe A. Further, the rotary mowing unit U is lighter than the hammer knife type. In addition, since the pair of grounding rings 65 arranged at both ends of the front end portion of the mowing unit U are configured so as not to be grounded even at the lowest position of the mowing unit U (the position with the shortest cutting height), the mowing unit The total weight of U acts as a cantilever at the front end of the machine A. With the main feature that the airframe A is driven by the rubber crawler 1, the above-mentioned matters are synergistic, and as shown in FIG. 9, on the slope slope 82 of the levee etc. When mowing, the running stability along the contour direction is increased, and the frequency at which the airframe A slips to the lower side of the slope slope 82 is greatly reduced. The amount is reduced. For this reason, even on soft sloped ground, the cutting work of the vegetation J can be performed relatively stably along the contour line direction. For this reason, the driving work performed while the driver M follows the airframe A behind the airframe A is also facilitated. Further, as shown in FIG. 10, when the airframe A moves in the direction of the arrow P along the contour line direction of the slope slope 82, the roots of the vegetation J growing on the slope slope 82 are grass cutting units. The cutting edge 41 hits the rubber cover 69 at the front end of the U, and the vegetation J is cut and cut by the root portion by the cutting blade 41 rotating at high speed, and the chopped vegetation is rotated by the cutting blade 41. Is sent to the right as viewed from the driver M (see FIG. 9).

Further, regarding the configuration of the rotary type mowing unit U, if the three cutting blades 41 are arranged as described above, there is an advantage that the total length (L ₀ ) of the mowing machine can be shortened. It is also possible to arrange as shown in FIG. Further, as shown in FIG. 11C, the two cutting blades 41 can be arranged in the oblique direction. Figure 11 (b), the total length of the mower with the arrangement of the cutting blade 41 shown in (c), respectively (L _1), a (L _2), the total length (L ₀ of mower of Example ), But shorter than the total length (L ₃ ) of the mower having one cutting blade.

1 is an overall schematic perspective view of a rubber crawler mower according to the present invention. It is a side view similarly. It is also a plan view. It is a perspective view of the principal part similarly. It is a top view which shows a power transmission system. It is a side view which shows that the mowing unit U raises / lowers and the cutting height of vegetation changes. It is a side view which shows the state in which the mowing unit U rotates with respect to the movable vertical link. (A) and (b) show that the mowing unit U is mounted on the projecting object 81 during mowing work, and the mowing unit U It is a side view which shows the state which contacted the part of the inclination angle different from a part. It is the figure which looked at the state which is cutting the vegetation of the slope slope 82 by the grass cutter which concerns on this invention from the back side of the grass cutter. It is a figure which shows the state in which the vegetation J is cut by the cutting blade 41 of the grass cutting unit U. It is a figure which shows that a difference arises in the full length of a mower by the number of the cutting blade 41, and its arrangement | positioning.

Explanation of symbols

A: Airframe
E: Engine
K: Parallel link mechanism
J: vegetation
U: Mowing unit
1: Rubber crawler
14: Movable vertical link
41: Cutting blade
45: Pruning pin of mowing unit
46: Vertical rotation axis of cutting blade
49: Gearbox
52: Input shaft of gearbox
65: Ground ring
81: Protrusion (obstacle)
82: Inclined slope

Claims (6)

In a mowing machine comprising a machine body having a pair of left and right rubber crawlers, and a mowing unit attached to the front part of the machine body,
The rubber crawler mower is characterized in that the mowing unit is a rotary type in which a cutting blade rotates about a vertical rotation axis. The mowing unit includes two cutting blades arranged at a predetermined interval in the left-right direction, and a rear position of the two cutting blades, and an intermediate position between the two cutting blades along the left-right direction. The rubber crawler type mower according to claim 1, comprising a total of three cutting blades, one cutting blade disposed on the blade. The mowing unit is normally supported horizontally by the gravitational action with respect to the frame of the fuselage, and when the tip hits an obstacle or the like, the mowing unit only rotates upward from the horizontal state to avoid the obstacle. The rubber crawler mower according to claim 1 or 2, wherein the rubber crawler mower is supported so as to be movable. The tip of the mowing unit is provided with a grounding ring that is not grounded in a mowing state with the lowest cutting height and can be grounded only on a surface inclined with respect to the grounding portion of the aircraft. A rubber crawler mower according to any one of claims 1 to 3. The rubber crawler mower according to any one of claims 1 to 4, wherein the mowing unit is connected to the machine body through a parallel link mechanism. In order to transmit the power of the engine mounted on the airframe to the mowing unit, the mowing unit supported by the input shaft of the gearbox mounted on the frame of the mowing unit and the movable vertical link constituting the parallel link mechanism. The rubber crawler mower according to claim 5, wherein the rotation fulcrum is arranged on the same axis.

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